The present invention relates to detection by a receiver of a sequence with a sequence detector, the sequence being transmitted by a transmitter. The sequence detector is determined by a code that is also transmitted to the receiver.
Linear Feedback Shift Registers (LFSRs) are known and are applied in applications such as sequence generators, scramblers, coders, descramblers and decoders. An LFSR can be a binary LFSR wherein a shift register element can hold a binary symbol, the binary symbol being represented by a binary signal. An LFSR can be a non-binary LFSR, wherein a shift register element can hold a non-binary symbol; a non-binary symbol having one of n states with n>2. A single non-binary symbol can be represented by a signal. In one embodiment such a signal representing a non-binary symbol can be a single non-binary signal able to have one of n states. A non-binary symbol in another embodiment can be represented by a plurality of signals, for instance, by a plurality of binary signals. For instance, an 8-state symbol can be represented by a word of 3 bits, each bit being represented by a binary signal.
A binary or n-state LFSR can be in Fibonacci or in Galois configuration.
In many applications, including in scrambling and descrambling and in spread-spectrum modulation a sequence of n-state symbols with n≥2 and n>2, some knowledge is required about a phase or synchronization of a sequence that was transmitted from a transmitter in order to be detected or decoded at a receiver. In the instant application, an n-state sequence is assumed to be associated with an n-state LFSR. In some cases one wants to know how a phase or synchronization point of a received sequence relates to an initial state of a sequence generator. In other cases one would like to start generating in parallel to a received sequence a sequence that is synchronized with the received sequence.
Different n-state LFSRs with n=2 or n>2 can be used to generate different n-state sequences that can be detected with corresponding sequence detectors. Applications of sequence generators and detectors are believed to be currently not available for unlocking or activating a mechanism. Accordingly novel and improved combinations of n-state LFSRs with n=2 or n>2 as sequence generators and detectors are required to activate a mechanism.